Do Capital Gains Keep the Lower Rate Under the AMT? (w/Examples) + FAQs

This article reflects federal rules as of June 2026 and covers tax year 2025 (the 2026 filing season), with 2026 changes flagged where they apply. State rules are noted separately. Tax law changes — confirm current figures before you file.

Quick Answer

Yes. For tax year 2025, long-term capital gains and qualified dividends keep the same preferential rates — 0%, 15%, or 20% — under the Alternative Minimum Tax (AMT) as under the regular tax. The AMT does not re-rate your gains. But large gains can still raise your AMT bill indirectly by shrinking your AMT exemption.

So the short version is reassuring, and the longer version is where people get burned. A capital gain is never taxed at the 26% or 28% AMT rate, because the AMT uses a separate worksheet that pulls your gains out and taxes them at the same favorable rates the regular tax uses. The trap is quieter: a big gain raises your alternative minimum taxable income, and once that income climbs past the phaseout line, your AMT exemption melts away — pushing the rest of your income into AMT.

For tax year 2025, roughly 200,000 taxpayers are projected to owe AMT, but the Tax Policy Center estimates that number could swell sharply once tighter 2026 phaseout rules take hold. Here is what you will learn:

💡 Why your capital gains keep the 0%/15%/20% rate even when you owe AMT.
⚠️ How a large gain can still raise your AMT bill by shrinking your exemption.
🧮 Three fully worked dollar examples showing the math line by line.
📅 What changes in 2026 under the One Big Beautiful Bill Act (OBBBA) — and why it matters more.
🛠️ Exactly which form to file, which records to keep, and when to call a pro.

What “AMT” Actually Means

The Alternative Minimum Tax is a second, parallel tax system. You figure your tax the normal way, then figure it again under AMT rules on Form 6251, and you pay whichever is higher. The AMT exists to stop high earners from using too many deductions and special breaks to wipe out their tax bill.

The AMT starts from your regular taxable income, then adds back certain items called preferences and adjustments. Common add-backs include your state and local tax deduction, the bargain element from exercising incentive stock options (ISOs), and interest from private activity bonds. The result is your alternative minimum taxable income, or AMTI — a plain term for “income as the AMT sees it.”

Against that AMTI, you get an AMT exemption — a flat amount the AMT lets you subtract before applying its rates. For tax year 2025, the exemption is $88,100 for single filers and $137,000 for married couples filing jointly. Whatever is left after the exemption is your “taxable excess,” taxed at just two AMT rates: 26% and 28%.

The consequence of ignoring the AMT is simple and costly: if your tentative AMT comes out higher than your regular tax, the difference is added to your bill. Miss it, and the IRS can assess the shortfall plus interest and penalties. The fix is to run Form 6251 before you file, especially in any year with a big income event.

Why Capital Gains Keep the Lower Rate

Here is the heart of the question. The AMT has only two stated rates, 26% and 28%, and both are higher than the top long-term capital gains rate of 20%. If the AMT taxed your gains at 28%, every investor with a big sale would get crushed. It does not.

Form 6251 carves your capital gains out before applying the 26%/28% rates. The form routes your net long-term capital gains and qualified dividends through the same capital gains worksheet used for the regular tax. Those gains are taxed at 0%, 15%, or 20% in both systems. Only your other income — wages, interest, ISO bargain element, and similar — faces the 26% or 28% AMT rate.

The “why” is built into the law. Congress wanted preferential capital gains rates to survive the AMT, so the AMT computation explicitly preserves them. The practical result: your $50,000 long-term gain is taxed at 15% whether you owe regular tax or AMT.

A common misconception is that owing AMT means all your income — gains included — gets hit at 28%. It does not. Your gains stay at their normal rate. What actually changes your bill is the indirect effect described next, which trips up far more people than the rate myth.

The takeaway for action: do not avoid a smart sale just because you fear the AMT will re-rate the gain — it will not. Instead, model the exemption phaseout effect before you sell.

The Hidden Trap: The Exemption Phaseout

The AMT exemption is not unlimited. Once your AMTI crosses a threshold, the exemption phases out — you lose part of it as your income rises. For tax year 2025, the phaseout begins at $626,350 for single filers and $1,252,700 for joint filers, and the exemption shrinks by 25 cents for every extra dollar of AMTI.

This is where capital gains sneak back into the picture. A large gain raises your AMTI — even though the gain itself keeps the 15% or 20% rate. The higher AMTI can push you past the phaseout line, melting away your exemption. That lost exemption means more of your ordinary income gets taxed at 26% or 28%.

So the gain is not re-rated, but it triggers a higher tax on your other income. Think of it as a side door: the gain walks in at 15%, but it leaves the exemption door open for the AMT to grab the rest.

The consequence is a higher effective tax rate during the phaseout band. Wealthspire estimates that an extra $100,000 of long-term gain landing in the phaseout zone can carry a roughly 34% effective federal cost once the exemption loss is counted — far above the 20% headline rate. The action step: in any year you expect both high income and a big gain, run Form 6251 to see if the phaseout swallows your exemption before you pull the trigger.

Which Situation Applies to You?

The answer to “will my gain cause AMT trouble?” depends entirely on your full picture. Use this to find the part that fits you.

You have a modest gain and income well under $200,000: You almost certainly stay under the AMT exemption, and your gain keeps its low rate with no AMT at all. Read the worked Example 1 below.
You exercised ISOs this year: The ISO bargain element is a major AMT add-back. This is the most common AMT trigger — read the ISO section and Example 2.
You have a very large one-time gain (home sale, business sale, concentrated stock): Your gain keeps its rate, but it may push you into the phaseout band and cost you part of your exemption. Read Example 3.
You live in a high-tax state (California, New York, New Jersey): Your disallowed state-tax deduction already pushes you toward AMT; a gain on top can tip you over. Read the state section.
Your income approaches or exceeds $1 million (joint): You are squarely in the new 2026 danger zone. Read the OBBBA section closely.

Worked Example 1 — The Gain Keeps Its Rate

Maria is single, lives in Texas (no state income tax), and has tax year 2025 wages of $120,000 plus a $40,000 long-term capital gain from selling stock. Her total income is $160,000.

Her AMTI is well below the $88,100 exemption phaseout start and even below the bracket where AMT bites. After subtracting the $88,100 exemption, her taxable excess is small, and her tentative AMT comes out lower than her regular tax. Maria owes no AMT.

Her $40,000 gain is taxed at the regular 15% long-term rate — $6,000 — in both systems. The AMT changes nothing for her. The lesson: most people with ordinary incomes and ordinary gains never touch the AMT, and the lower capital gains rate is fully intact.

Maria’s 2025 Numbers	Amount
Wages	$120,000
Long-term capital gain	$40,000
Tax on gain (15%)	$6,000
AMT owed	$0

Worked Example 2 — ISOs Trigger the AMT

David is single and exercises incentive stock options in 2025. He pays $20,000 to buy shares worth $200,000 and holds them. For the regular tax, this exercise is invisible — no income. For the AMT, the $180,000 bargain element is added back on Form 6251, line 2i.

Add David’s $215,000 of regular income to the $180,000 ISO add-back and his AMTI climbs near $395,000. After his $88,100 exemption, a large taxable excess gets taxed at 26%/28%. His AMT exceeds his regular tax, so he owes the difference — using Mercer Advisors’ similar figures, AMT can add roughly $17,000 to a comparable bill.

Notice: David has no capital gain here. His AMT is driven entirely by the ISO bargain element, not by any sale. If he later sells the shares, the AMT he paid often becomes a minimum tax credit on Form 8801 he can recover. The action step: model an ISO exercise before year-end and consider spreading exercises across years.

David’s 2025 Numbers	Amount
Regular income	$215,000
ISO bargain element (AMT add-back)	$180,000
AMTI (approx.)	$395,000
Extra AMT owed (approx.)	$17,000

Worked Example 3 — A Big Gain Shrinks the Exemption

Susan and Tom are married filing jointly in 2025. They have $900,000 of ordinary income and sell a business asset for a $400,000 long-term capital gain, bringing AMTI to about $1,300,000.

Their gain itself is taxed at 20% — $80,000 — in both systems, exactly as the rule promises. But their AMTI of $1.3 million sits past the $1,252,700 joint phaseout start for 2025. The exemption shrinks by 25 cents per dollar over the line, stripping away part of their $137,000 exemption and exposing more ordinary income to the 28% AMT rate.

So the gain kept its 20% rate, yet it still raised the family’s total tax by eroding the exemption. The extra cost is not on the gain — it is on the ordinary income that lost its shelter. The action step: when a large sale is coming, ask whether deferring part of it to a lower-income year keeps the exemption intact.

Susan & Tom’s 2025 Numbers	Amount
Ordinary income	$900,000
Long-term capital gain	$400,000
Tax on gain (20%)	$80,000
AMTI	$1,300,000
Exemption status	Partially phased out

What Changes in 2026 Under OBBBA

The One Big Beautiful Bill Act made the higher AMT exemption permanent — good news — but it tightened the phaseout dramatically starting in tax year 2026. This is the single most important planning shift for anyone with gains or ISOs.

Two changes matter. First, the phaseout thresholds drop to about $500,000 (single) and $1,000,000 (joint) — far lower than 2025’s $626,350 and $1,252,700. Second, the phaseout rate doubles from 25% to 50%, so the exemption disappears twice as fast.

The combined effect is that a 2026 married couple’s exemption is fully gone at roughly $1.28 million of AMTI, versus about $1.8 million under 2025 rules. The same gain or ISO exercise that was harmless in 2025 can trigger real AMT in 2026.

Capital gains still keep their 0%/15%/20% rate in 2026 — that does not change. What changes is how fast a gain can push you into the phaseout band and cost you your exemption. The action step: if you have a big gain or ISO exercise planned, compare the cost of doing it in 2025 versus 2026, because timing now matters far more.

These OBBBA AMT changes are permanent, not a temporary sunset — but tax law can shift, so confirm the current thresholds before acting.

Does My State Follow This?

Federal AMT is only half the story. Most states do not have their own AMT, so for the majority of taxpayers the state question is moot — your state simply taxes your capital gains at its ordinary rates.

A few states are exceptions. California still imposes a state AMT (Schedule P, Form 540) with its own exemption and phaseout, and a handful of others have AMT-like provisions. California taxes capital gains as ordinary income regardless, so the state AMT rarely changes a gain’s treatment, but it can apply to ISO exercises.

The action step: separate the two questions. First confirm your federal AMT on Form 6251. Then check whether your state has its own AMT form — and never assume your state copies the federal rules, because conformity genuinely varies.

How to Report It: Form 6251

Form 6251 is where the AMT is calculated. You attach it to your Form 1040 if your tentative minimum tax exceeds your regular tax, or if certain credits or preference items apply. The form walks line by line from your regular taxable income to your final AMT.

Key lines for our topic: line 2i captures the ISO bargain element, line 2g captures private activity bond interest, and the capital gains worksheet inside the form preserves your 0%/15%/20% rates. The exemption and its phaseout are figured on lines 5 and 6. If you want a deeper walkthrough, see our How to Fill Out Form 6251 guide and the companion Schedule D and Form 8949 guide for reporting the gains themselves.

The deadline is your normal return deadline — April 15, 2026, for tax year 2025, or October 15, 2026, with an extension. Missing the AMT does not extend your deadline; it just invites an IRS notice later. If you paid AMT because of ISOs, also keep Form 8801 on your radar to recover the credit in future years.

Deadlines, Costs, and Timing

Timing is everything with the AMT, because most AMT pain comes from when you recognize income, not whether you do. A gain or ISO exercise stacked into a single high year does far more damage than the same amount spread across two years.

The filing deadline for tax year 2025 is April 15, 2026. Estimated taxes matter too — a big mid-year gain can require a quarterly estimated payment to avoid an underpayment penalty. Doing your own Form 6251 with tax software is usually free to modest in cost. A CPA’s multi-year AMT projection typically runs a few hundred to a couple thousand dollars, and for a seven-figure income event it usually pays for itself.

Mistakes to Avoid

Assuming the AMT re-rates your gains at 28%. It does not — but believing it leads people to skip smart sales and lose real money.
Forgetting the exemption phaseout. You focus on the gain’s rate and miss that the gain shrank your exemption, raising tax on other income.
Exercising ISOs without modeling AMT first. The bargain element is invisible to regular tax but a major AMT add-back, producing a surprise bill.
Stacking income into one year. A single huge-income year wastes your exemption; spreading income across years often saves thousands.
Ignoring the 2026 OBBBA changes. The faster, lower phaseout means a 2026 gain can trigger AMT that the same 2025 gain would not.
Skipping Form 6251 entirely. If you only run the regular tax, you never see the AMT coming, and the IRS assesses it with interest later.
Treating AMT as a permanent loss. ISO-driven AMT often creates a recoverable credit on Form 8801 — failing to track it forfeits future savings.
Assuming your state mirrors federal rules. California and a few others have their own AMT; guessing wrong understates your bill.

Do’s and Don’ts

Do run Form 6251 in any year with a large gain, an ISO exercise, or unusually high income — because the AMT is invisible until you calculate it.
Do anchor every figure to its tax year, since 2025 and 2026 thresholds differ sharply.
Do track AMT paid on ISOs, because it can become a credit you recover later.
Do consider spreading income across years, since the exemption resets annually.
Do separate the federal and state questions, because most states have no AMT but a few do.
Don’t assume your capital gains lose the lower rate — they keep 0%/15%/20% under AMT.
Don’t ignore the phaseout band, because that is where the real cost hides.
Don’t exercise ISOs late in the year without a projection, since you lose the chance to adjust.
Don’t rely on a single-year estimate, because AMT is a multi-year story.
Don’t treat online figures as current, since OBBBA changed the rules for 2026.

Pros and Cons of the AMT’s Capital Gains Treatment

Pro: Your gains keep the preferential 0%/15%/20% rate, so the AMT never taxes a long-term gain at 28%.
Pro: Qualified dividends get the same protection, preserving favorable rates on investment income.
Pro: ISO-driven AMT often creates a recoverable credit, so it can be a timing cost, not a permanent one.
Pro: The 2025 exemption is large enough that most middle earners never owe AMT at all.
Pro: The OBBBA made the higher exemption permanent, removing the old uncertainty over expiration.
Con: A large gain can still raise AMT indirectly by shrinking the exemption, surprising taxpayers.
Con: The 2026 phaseout is faster and starts lower, expanding who gets caught.
Con: ISO exercises can trigger AMT on paper gains you never received in cash.
Con: The math is complex, often requiring software or a professional.
Con: State AMT in places like California adds a second layer of complexity.

What to Do Next

Pull your numbers. Gather your wages, capital gains (Schedule D / Form 8949), ISO Form 3921, and any private activity bond interest.
Run Form 6251. Use tax software or a worksheet to compare your tentative AMT to your regular tax for tax year 2025.
Check the phaseout. If your AMTI is near $626,350 (single) or $1,252,700 (joint) for 2025, model how a gain affects your exemption.
Plan timing for 2026. Compare doing a big gain or ISO exercise in 2025 versus the tighter 2026 rules.
Track any AMT credit. If you owe AMT from ISOs, note it for Form 8801 recovery in later years.
Call a professional if your income approaches seven figures, you have ISOs, or you face a large one-time sale — a multi-year AMT projection usually pays for itself.

This article is educational and not a substitute for advice from a licensed CPA or tax attorney for your specific situation.

FAQs

Are long-term capital gains taxed at 28% under the AMT?

No. For tax year 2025, long-term gains keep the 0%, 15%, or 20% rate under both the regular tax and the AMT. The 26%/28% AMT rates apply only to your other income, not your gains.

Can capital gains cause me to owe AMT?

Yes, indirectly. A large gain raises your AMTI and can push you past the exemption phaseout, shrinking the exemption and exposing more ordinary income to AMT — even though the gain itself keeps its low rate.

Do qualified dividends keep their lower rate under the AMT?

Yes. For tax year 2025, qualified dividends are taxed at the same 0%/15%/20% preferential rates under the AMT as under the regular tax, through Form 6251’s capital gains worksheet.

What triggers the AMT most often?

Incentive stock options. The ISO bargain element is a major AMT add-back invisible to the regular tax. High state taxes and large one-time income events are other common triggers.

What is the AMT exemption for 2025?

$88,100 for single filers and $137,000 for married filing jointly, per the 2025 Form 6251 instructions. It phases out above $626,350 (single) and $1,252,700 (joint).

How does OBBBA change the AMT in 2026?

Faster phaseout. Starting in 2026, thresholds drop to about $500,000 (single) and $1,000,000 (joint), and the phaseout rate doubles to 50%, so the exemption disappears twice as fast.

Will my capital gains rate change in 2026?

No. Long-term gains still keep the 0%/15%/20% rates in 2026. What changes is how quickly a gain can push you into the AMT exemption phaseout band.

What form do I use to figure the AMT?

Form 6251. Attach it to your Form 1040 when your tentative minimum tax exceeds your regular tax. The capital gains worksheet inside it preserves your favorable rates.

Can I get back the AMT I paid on ISOs?

Yes, often. AMT driven by ISO timing usually creates a minimum tax credit on Form 8801 that you can use in future years when your regular tax exceeds your AMT.

Does my state have its own AMT?

Usually no. Most states lack an AMT, so they tax gains at ordinary state rates. California is a notable exception with its own state AMT on Schedule P (Form 540).

When is the AMT due for tax year 2025?

April 15, 2026. The AMT follows your normal return deadline, October 15, 2026, with an extension. A large mid-year gain may also require a quarterly estimated payment.

Does a home sale trigger the AMT?

Rarely directly. The gain keeps its capital gains rate, but a very large taxable home gain can raise AMTI enough to shrink your exemption if you are already a high earner.

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